Convert master_manager_launcher to use multiprocessing.

infra/libs/process_invocation/test/multiprocess_test.py

Index: infra/libs/process_invocation/test/multiprocess_test.py
diff --git a/infra/libs/process_invocation/test/multiprocess_test.py b/infra/libs/process_invocation/test/multiprocess_test.py
new file mode 100644
index 0000000000000000000000000000000000000000..eb2503946a2026a3d6d28cc45d315fb747ce310c
--- /dev/null
+++ b/infra/libs/process_invocation/test/multiprocess_test.py
@@ -0,0 +1,48 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import multiprocessing
+from testing_support import auto_stub
+
+from infra.libs.process_invocation import multiprocess
+
+
+class TestMultiprocess(auto_stub.TestCase):
+  def setUp(self):
+    super(TestMultiprocess, self).setUp()
+
+    self.calls = set()
+    class FakePool(object):
+      def __init__(self, calls):
+        self.calls = calls
+
+      def close(self):
+        self.calls.add('close')
+
+      def terminate(self):
+        self.calls.add('terminate')
+
+      def join(self):
+        self.calls.add('join')
+
+    def pool_maker(*_args, **_kwargs):
+      return FakePool(self.calls)
+
+    self.mock(multiprocessing, 'Pool', pool_maker)
+
+  def testMultiprocess(self):
+    with multiprocess.MultiPool(16) as _pool:
+      pass
+
+    self.assertIn('close', self.calls)
+    self.assertIn('join', self.calls)
+    self.assertNotIn('terminate', self.calls)
+
+  def testMultiprocessTermiantes(self):
+    with self.assertRaises(RuntimeError):
+      with multiprocess.MultiPool(16) as _pool:
+        raise RuntimeError('a super bad error')
+
+    self.assertIn('terminate', self.calls)
+    self.assertIn('join', self.calls)